1 Now, it is clear from this that those who obtain ultimate felicity as a result of the divine vision never depart from it.

2 For, “everything which at one time exists, and at another does not, is measured by time,” as is clear in Physics IV [12: 221b 28]. But the aforementioned vision, which makes intellectual creatures happy, is not in time but in eternity. So, it is impossible for a person to lose it, once he has become a partaker in it.

Notes The distinction between being in time and in eternity is crucial. And also a disproof that does not not exist, which is to say, time certainly exists for us.

3 Again, the intellectual creature does not reach his ultimate end until his natural desire comes to rest. But, just as one naturally desires felicity, so also does he naturally desire everlasting felicity; for, since he is everlasting in his substance, he desires to possess forever that object which is desired for its own sake and not because of something else. Therefore, his felicity would not be the ultimate end unless it endured perpetually.

4 Besides, everything that is possessed with love may cause sorrow, provided it be recognized that such a thing may be lost. But the aforesaid vision which makes men happy is especially loved by its possessors, since it is the most lovable and desirable of objects. Therefore, it would not be possible for them to avoid sorrow if they knew that they would lose it at some time. Now, if it were not perpetual, they would know this, for we have shown already, that, while seeing the divine substance, they also know other things that are naturally so. Hence, they certainly know what kind of vision it is, whether perpetual or to stop at some future time. So, this vision would not be theirs without sorrow. And thus it will not be true felicity which should be made free from all evil, as we showed above.

5 Moreover, that which is naturally moved toward something, as to the end of its motion, may not be removed from it without violence, as in the case of a weight when it is thrown upward. But from what we have said, it is obvious that every intellectual substance tends by natural desire toward that vision. So, it cannot fail to continue that vision, unless because of violence. But nothing is taken away from a thing by violence unless the power removing it is greater than the power which causes it. Now, the cause of the divine vision is God, as we proved above. Therefore, since no power surpasses the divine power, it is impossible for this vision to be taken away by violence. Hence, it will endure forever.

Notes Sin is violence.

6 Furthermore, if a person ceases to see what he formerly saw, this cessation will be either because the power of sight fails him, as when one dies or goes blind, or because he is impeded in some other way, or it will be because he does not wish to see any longer, as when a man turns away his glance from a thing that he formerly saw, or because the object is taken away. And this is true in general whether we are talking about sensory or intellectual vision.

Now, in regard to the intellectual substance that sees God there cannot be a failure of the ability to see God: either because it might cease to exist, for it exists in perpetuity, as we showed above, or because of a failure of the light whereby it sees God, since the light is received incorruptibly both in regard to the condition of the receiver and of the giver. Nor can it lack the will to enjoy such a vision, because it perceives that its ultimate felicity lies in this vision, just as it cannot fail to will to be happy. Nor, indeed, may it cease to see because of a removal of the object, for the object, which is God, is always existing in the same way; nor is He far removed from us, unless by virtue of our removal from Him. So, it is impossible for the vision of God, which makes men happy, ever to fail.

7 Again, it is impossible for a person to will to abandon a good which he is enjoying, unless because of some evil which he perceives in the enjoyment of that good; even if it be simply that it is thought to stand in the way of a greater good. For, just as the appetite desires nothing except under the rational character of a good, so does it shun nothing except under the character of an evil.

But there can be no evil in the enjoyment of this vision, because it is the best to which the intellectual creature can attain. Nor, in fact, can it be that he who is enjoying this vision might think that there is some evil in it, or that there is something better than it. For the vision of the highest Truth excludes all falsity. Therefore, it is impossible for the intellectual substance that sees God ever to will to be without that vision.

Notes In other words, sin won’t be possible.

8 Besides, dislike of an object which one formerly enjoyed with delight occurs because this thing produces some kind of real change, destroying or weakening one’s power.

And this is why the sense powers, subject to fatigue in their actions because of the changing of the bodily organs by sense objects, are corrupted, even by the best of such objects. Indeed, after a period of enjoyment, they grow to dislike what they formerly perceived with delight.

And for this reason we even suffer boredom in the use of our intellect, after a long or strenuous meditation, because our powers that make use of the bodily organs become tired, and intellectual thinking cannot be accomplished without these. But the divine substance does not corrupt; rather, it greatly perfects the intellect. Nor does any act exercised through bodily organs accompany this vision. Therefore, it is impossible for anyone who at one time took joy in the delight of this vision to grow weary of it.

Notes This third paragraph is also pertinent to our discussion of intelligence.

9 Furthermore, nothing that is contemplated with wonder can be tiresome, since as long as the thing remains in wonder it continues to stimulate desire. But the divine substance is always viewed with wonder by any created intellect, since no created intellect comprehends it. So, it is impossible for an intellectual substance to become tired of this vision. And thus, it cannot, of its own will, desist from this vision.

Notes Recall, too, that there are hierarchies of infinity; they become so rich and dense that it is impossible to exhaust them, even in eternity.

10 Moreover, if any two things were formerly united and later come to be separated, this must be due to a change in one of them. For, just as a relation does not come into being for the first time without a change in one of the things related, so also it does not cease to be without a new change in one of them.

Now, the created intellect sees God by virtue of being united to Him in some way, as is clear from what we have said. So, if this vision were to cease, bringing this union to an end, it would have to be done by a change in the divine substance, or in the intellect of the one who sees it. Both of these changes are impossible: for the divine substance is immutable, as we showed in Book One [13], and, also, the intellectual substance is raised above all change when it sees God’s substance. Therefore, it is impossible for anyone to depart from the felicity in which he sees God’s substance.

11 Besides, the nearer a thing is to God, Who is entirely immutable, the less mutable is it and the more lasting. Consequently, certain bodies, because “they are far removed from God,” as is stated in On Generation II [10: 336b 30], cannot endure forever. But no creature can come closer to God than the one who sees His substance. So, the intellectual creature that sees God’s substance attains the highest immutability. Therefore, it is not possible for it ever to lapse from this vision.

12 Hence it is said in the Psalm (83:5): “Blessed are they who dwell in Your house, O Lord: they shall praise You for ever and ever.” And in another text: “He shall not be moved for ever that dwells in Jerusalem” (Ps. 124: 1) And again: “Your eyes shall see Jerusalem, a rich habitation, a tabernacle that cannot be removed; neither shall the nails thereof be taken away for ever; neither shall any of the cords thereof be broken, because only there our Lord is magnificent” (Is. 33:20-21). And again: “He who overcomes, I will make him a pillar in the temple of My God: and he shall go out no more” (Rev. 3:12)

13 By these considerations, then, the error of the Platonists is refuted, for they said that separated souls, after having attained ultimate felicity, would begin to desire to return to their bodies, and having brought to an end the felicity of that life they would again become enmeshed in the troubles of this life; and also the error of Origen, who said that souls and angels, after beatitude, could again return to unhappiness.

Great book on the subject is Infinity and the Mind: The Science and Philosophy of the Infinite by Rudy Rucker. In it he speaks of the hierarchies of the infinite, how they pile up and eventually become incomprehensibly (in a quite literal way) infinite. Has striking ties to the ontological argument.